For many decades self-propelled combine harvesters have been used by farmers to harvest a wide range of crops including cereals, maize and oil seed rape. Typically a combine harvester cuts the crop material, threshes the grain therefrom, separates the grain from the straw and cleans the grain before storing in an on-board tank. Straw and crop residue is ejected from the rear of the machine.
The crop processor of a combine harvester comprises threshing and separating apparatus. The separating apparatus is traditionally based upon one of two well-established systems. In a first known system straw walkers are used to ‘walk’ the crop stream rearwardly in the combine wherein agitation caused by this movement causes the grain to fall through an integrated grate whilst the straw residue falls from the rear and out of the combine. In the second alternative system one or two cylindrical rotors are mounted within the combine longitudinally and enclosed by rotor cages wherein crop fed in at the front by a tangential-flow impelling feed beater, travels rearwardly in an axially spiral motion due to interacting crop engaging elements fitted to the rotor tube and guide vanes fitted on the inside of the rotor cage. The cylindrical rotors can provide a threshing and separating action, or a separating action only. Separated grain falls through a grate in the cage whilst the straw residue is conveyed rearwardly and out of the machine. The invention is concerned with driving a feed beater in this second system of separating apparatus.
The feed beater is commonly driven by a belt-drive system comprising belts and pulleys, the beater drive typically comprising a power branch deriving its torque from a main drive system driven by an internal combustion engine. A clutch is typically included in the driveline to allow the operator to selectively engage and disengage the crop processing apparatus which includes, inter alia, the feed beater, the separating apparatus and a grain cleaning shoe.
Combine harvesters are utilized for harvesting a wide range of different crops. It is recognized that certain crops, such as corn or beans, can become damaged if the feed beater rotates too fast. Due to the feed beater being drivingly connected to the other crop processing systems or indeed the engine, it is not possible or practical for the operator to slow down the feed beater without affecting the other systems without the provision of a multi-ratio drive to the feed beater.
It is known to provide a stepped multi-ratio drive system for a feed beater but such systems involve many additional components and, as a result, are expensive. Moreover, changing the drive speed of the beater is cumbersome and cannot be done whilst the harvester is operating.